A conventional set of golf clubs includes a series of woods used for shots from a tee or fairway, a series of irons used for shorter shots, and a putter used on the green. Traditional woods have heads made of a hardwood, such as persimmon. However, in recent years real wood has been substantially replaced by metal heads comprising a hollow cast shell filled with a synthetic plastic foam. For purposes of this disclosure, the resulting club shall be termed a metal "wood."
A recent development in metal "woods" has been the production and use of larger sized metal "wood" club heads. Enlargement of the club face area on such a club results in enlargement of the "sweetspot" area. This is the area wherein the center of gravity of the club head is directly behind the point at which a golf ball is being struck by the club.
While it is not practical to produce oversize club heads from natural wood, due to their solid construction and resulting increases in weight as a function of size, the hollow nature of metal "wood" clubs provides the club designer with an opportunity to substantially vary the size and configuration of such club heads. Metal "woods" are today manufactured and sold in a normal size generally corresponding to the size of a natural wood club head, a midsize having a slightly increased club face area, and in oversize or jumbo sizes that are very distinctly larger than a conventional club head. A significant design limitation of such larger club heads is that maintaining normal ranges of club head weight seriously restricts the thicknesses of the walls about the hollow shell forming such heads.
When designing hollow metal club heads of increased size, the average thickness of the larger surface areas encountered about a club head must be correspondingly decreased. This has resulted in weakening and collapse of club faces due to the failure of the unsupported span of metal across the club face, which often is incapable of withstanding the impact of a golf ball being struck by the club head. Many such clubs have failed because the weakened club face structure cannot withstand the maximum impact forces to which they can be subjected during normal play.
One response to the structural limitations of metal "wood" club faces in larger sized club heads has been to provide integral bracing at the rear surface of the club face. This can take the form of vertical and/or horizontal ribs, as well as enclosed cells that strengthen the club face area and structurally resist ball impact forces. However, there are limits to the amount of integral bracing that can be provided at the club face without either increasing the weight of the club head beyond permissible design limits or substantially sacrificing thickness in other areas of the hollow club head shell.
This invention was developed in an effort to structurally strengthen the club face of a metal "wood" having a larger sized club head without sacrificing the desired increased area and height of the club face available for striking a golf ball. In addition, the improvement described below slightly lowers the sweetspot on an enlarged club face. The result of this improvement is a structurally strengthened club face without diverting substantial mass and weight to internal bracing at the back of the club face.